1. Field of the Invention
This invention generally relates to medical instruments and more specifically to an extractor for removing an object from a body, particularly calculi that can form in the biliary and urinary systems.
2. Description of Related Art
Recently developed medical instruments reduce the invasiveness and potential trauma previously associated with various medical procedures. The removal of calculi in the form of kidney stones, gallstones and the like from the body is one area where this effort is meeting with success. Various instruments now permit the removal of kidney stones and gallstones without the need for major surgery. Some of these instruments incorporate miniaturized grasping forceps. This invention, however, is directed to an alternative set of instruments that utilize mechanical retrieval baskets.
The following United States Letters Patents and United States Patent Application describe various types of such retrieval baskets:
U.S. Pat. No. 4,346,846 (1982) Dormia
U.S. Pat. No. 4,590,938 (1986) Segura et al.
U.S. Pat. No. 4,611,594 (1986) Grayhack et al.
U.S. Pat. No. 4,625,726 (1986) Duthoy
U.S. Pat. No. 4,807,626 (1989) McGirr
U.S. Pat. No. 5,064,428 (1991) Cope et al.
Ser. No. 08/258,121 (1994) Bates et al.
Dormia discloses a retrieval basket at a distal end of a surgical extractor selectively extended beyond a tube in an enlarged condition. The retrieval basket comprises a plurality of wire pairs with the wires in the pairs extending in opposite helical wound paths to provide relatively closer wire spacings in the distal end of the enlarged retrieval basket compared to the proximal end. The differential wire spacing promotes the capture of objects in the middle portion of the retrieval basket and entrapment of such objects in the distal end of the retrieval basket.
Segura et al. disclose a medical retrieval device that can be inserted through the working channel of an endoscope for removing stones and the like from the kidneys or the ureter or biliary duct. A retrieval basket of relatively large diameter extends from the distal end of a sheath and collapses into a compact form when drawn into the sheath. Individual outwardly bowed spring strips form the retrieval basket. These strips extend generally axially of the sheath and join at respective distal and proximal ends. The retrieval basket has a generally bulbous form which is relatively stiff due to the spring strip construction and facilitates dislodgment and capture of stones.
The Grayhack et al. patent discloses another retrieval basket that is useful during the removal and/or destruction of calculi. A smooth outer tubular sheath overlies and contains a stranded wire cable terminating in a protective tip at the working or distal end of the device. When the cable is extended distally, the individual spring wire strands at the working end of the cable expand to form a retrieval basket. The distal end of this device additionally includes an expandable distal portion for protecting surrounding tissue during withdrawal of the device and calculi.
The Duthoy patent discloses an extraction device that includes a retrieval basket formed from a plurality of individual wires spaced about and outwardly from an imaginary extension of the center line of a hollow cable. A filiform extends distally from the distal end of the retrieval basket to extend past a stone and to allow the basket to be threaded around and onto the calculi.
The McGirr patent discloses an extractor including a self-closing retrieval basket at the distal end of a catheter with a flexible control line for opening the retrieval basket from the proximal end of the catheter. The retrieval basket assumes a normal position wherein it is in a compact closed form. Pulling on the control line flexes individual strips which define the retrieval basket to open the retrieval basket. When the control line is released, the strips relax and surround the calculi or object being removed.
Cope et al. disclose a stone retrieval basket having superelastic individual wire loops secured together at the apex of the loops to define a distal end of a retrieval basket which can be insert through and beyond a distal end of an elongated tube. Sleeves which secure the wires in a spaced relation and defines the proximal end of the retrieval basket, so the retrieval basket has a bulbous shape.
Bates et al. disclose, in a co-pending patent application commonly assigned with this application, a surgical retrieval basket comprising axially extending wires that are grouped in sets of filaments. The wires are normally maintained in an overlying sheath in a compact condition and form an enlarged retrieval basket upon retraction of the sheath. The individual filaments in a set are relatively closely angularly spaced with the sets being relatively widely spaced to provide a greater number of contact points with entrapped calculi without significantly increasing the manipulations necessary to capture such calculi in the retrieval basket.
These and other surgical extractors using retrieval baskets have certain common characteristics. Each retrieval basket comprises a plurality of filaments in the form of individual strands, strips or wires that extend from a proximal end of the retrieval basket to the distal end of the retrieval basket and, as disclosed by Cope et al., back to the proximal end. In some retrieval baskets the strands are formed along substantially straight lines when the retrieval basket is in a compact form; in others, along a generally helical path. Each instrument includes a plurality of three or more such individual strands to provide contact points for entrapping objects and between which the objects must pass for capture within the retrieval basket.
Retrieval baskets preferably include sufficient numbers of closely spaced wires to provide an enclosure for retaining objects captured within such retrieval baskets while having relatively few widely spaced wires for promotion of capture of such objects. Additionally, the overall size or diameter of an extractor and ancillary equipment, such as an endoscopic device, can impose upper limits on the number of wires and the size of the individual wires. Thus, the design of such baskets involves a compromise between the numbers of wires needed to retain objects and to promote capture of such objects and the overall size of such wires for sufficient strength of the basket.
The following United States Letters Patents and United States Patent Application describe retrieval baskets that include a material coating over the distal end of the baskets to encapsulate objects to be removed from the body:
U.S. Pat. No. 3,472,230 (1969) Fogarty
U.S. Pat. No. 4,790,812 (1988) Hawkins, Jr. et al.
Fogarty discloses a surgical retrieval basket that extends from the distal end of a catheter and comprises four spring wires that to a slide. An umbrella of suitable flexible material is connected to the distal portion of the wires so that upon deployment of the retrieval basket the edges of the umbrella form a circular scrapper. Retracting the retrieval basket from a deployed condition toward and then into a proximal sheath removes debris from a body passage with the umbrella retaining and then closing upon the captured debris.
Hawkins, Jr. et al. disclose a parachute retrieval basket deployed from the end of a catheter. The retrieval basket comprises four individual helically wound spring wires that extend between proximal to distal ends of the basket. A thin, porous fabric web secures and covers the distal portion of the wires to thereby prevent passage of debris, such as emboli or atheroma therethrough.
These and other surgical extractors having a unitary material web at the distal end have certain common characteristics. Each retrieval basket comprises a plurality of filaments in the form of individual strands, strips or wires that extend from a proximal end to the distal end of the retrieval basket. Like the previously described retrieval baskets, the strands lie either along substantially straight lines or extend along a generally helical path when the retrieval basket is in a compact form. The retrieval baskets include at least four individual strands to which the web is attached along a distal portion.
The design of a web retrieval basket is also a compromise between (1) the numbers of the strands necessary to deploy the web in a sufficiently open, radially-extended edge, (2) the numbers of wires to promote passage of objects through the wires into the retrieval basket, and (3) the overall size or diameter of an extractor and ancillary equipment, such as an endoscopic device with which the retrieval basket is used. These web baskets, however, are more difficult to manufacture than wire retrieval baskets, and further limit the diameter of the wires due to the space occupied by the web in the compacted condition.
Thus, additional wires in either a wire or web retrieval basket would be advantageous in certain respects and detrimental in others. For example, increasing the number of wires increases the number of contacts between the basket and any entrapped calculi and, in the case of a web basket more evenly opens the parachute. However, the resulting decrease in the spacing between such wires complicates the manipulations necessary for an expanded retrieval basket of either type to capture the calculi. Likewise, reducing the numbers of wires facilitates the capture of the object between the wires and selective release of the object, if needed. However, the fewer contact points between the captured object and the retrieval basket make retention and entrapment of such objects more difficult and, in the web basket, limit the radial extent of the web.
Additionally, most of these devices do not permit the retrieval basket to be dragged proximally along a surface to engage objects therealong. This would be particularly useful in the case of impacted calculi, e.g., kidney stones, that now frequently require major surgery due to the inability of the prior art devices to remove them. Thus, while the devices described above have some of the desirable features, none provide a device that is relatively simple to manufacture, promotes ease of capture of objects, promotes ease of percutaneous release of such objects, and promotes retention of relatively small objects captured.
Therefore it is an object of this invention to provide a surgical extractor that increases the reliability of retaining entrapped objects in a retrieval basket.
Another object of this invention is to provide a surgical extractor that increases the number of contact points with entrapped objects in a distal portion of a retrieval basket without increasing the overall size of the instrument.
Still another object of this invention is to provide a surgical extractor that promotes the selective release of entrapped objects.
Another object of this invention is to provide a surgical extractor that enables the entrapment of objects embedded in bodily tissue.
Still another object of this invention is to provide a surgical extractor that increases the number of contacts with entrapped calculi in an extractor that is readily manufactured.
Still yet another object of this invention is to provide a surgical extractor that increases the number of contact points with entrapped calculi and promotes ease of capture of such calculi.
Still a further object of this invention is to provide a surgical extractor that provides an open wire web of a plurality of filaments in a distal portion and individual strands in a proximal portion to optimize both the entry and capture of objects in the proximal portion of the retrieval basket and retention of such objects in the distal portion of the retrieval basket.
Yet a further object of this invention is to provide a surgical extractor that provides relatively few individual wire strands to promote capture of objects.
Yet still a further object of this invention is to provide a surgical extractor that decreases the number of interfering contact point wires with an object at the proximal portion of the extractor while maximally increasing the number of contacts with the object at a distal portion to retain such object.
In accordance with this invention a surgical extractor for removing an object from a body includes a retrieval basket with distal and proximal ends and a retractable sheath. The retractable sheath in a first position retains the retrieval basket in a compact condition and in a second position frees the retrieval basket for expansion to form an enlarged basket that comprises a plurality of wires extending between the distal and proximal ends of the basket. Each of the wires of the basket comprises a first section having an individual strand extending from one end, such as the proximal end, of the basket and a second section having a plurality of individual filaments that extend between the other end, such as the distal end, of the basket and the strand.
According to another aspect of this invention a surgical extractor for removing an object from a body comprises a handle extending along an axis that includes a base for being grasped by a physician and a slider for axial reciprocation relative to the base. The base connects with basket forming means for forming a enlarged basket distally of the handle. The basket includes a set of spaced, spring formed wires with each of the wires have a first section comprising an individual strand and a second section comprising a plurality of spaced filaments of wires. A sheath connects to the slider for axial displacement with respect to the basket whereby the sheath in a first position retains the wires and in a second position exposes the first and second sections of the wires to enable the wires to expand and form the basket.
According to a further aspect of this invention a surgical extractor for removing objects from a body comprises an axially extending, molded plastic, partially hollowed base and a support. The support includes a solid stainless steel, radially flexible, axially stiff rod attached to and extending distally from the base, a stainless steel cable extending distally from the rod and a connector axially connecting the rod and cable. A plurality of spaced stainless steel wires attached to the distal end of said cable. Each wire has a proximal portion comprising an individual strand and a distal portion comprising a plurality of filaments. Proximal movement of a plastic slider captured in the base moves a polyimide sheath and exposes the wires whereby the sheath compacts and retains said wires at substantially a given diameter in its distal position and releases the wires from their compact form to thereby form an enlarged retrieval basket.